Method of casting glass



Dec. 19, '1950 R. c. CLEVELAND ETAL 2,534,415

METHOD 0F CASTING GLASS Filed Jan. 11, 194e Sttnmspa Patented Dec. 19, 1950 i ED AT ES I Ef 2,534,415.l l'tEE'E-HGDlOF CASSING GIZASS Robert Q.,1Cle`v.eland and Williamg'Howard Said,

Corning, NL` Y., asvsignor's4 to.` Corning Glass Works, Corning, N:` Y,

York

a; corporation of New Agpiicatig January 11, 1946f.S:r..al,N 640,403;

The present. inventionfrelates to the. casting 0f glass, and is particularly concerned with a.

methodloimassproduction oi 'optical quality cane of? a desired cross-sectional configuration.

Inthe past it hasbeen repeatedly proposedto make cane ofja desired cross-sectional configura.- tionand tothen saw the same transversely into lensblanls of 'the desired thicknesses. However, the problem of'producing cane of` optical quality glass has been.A a. barrier,l to the successfull productionoblanks of high grade optical glass in this fashionas by all formerly known methods cords or striae.l were invariably introduced into the glass during its formation into cane, and its optical quality thus destroyedyor atleast greatly impaired.

The primev object ofthe present invention is a method of production of cane directly from a supply. body of highly reined, glass without the introduction., of cord, striae or. they like,lintothe argduat.,

Another4 object is a methcdofproduction of glass cane of.v opticalA qualityand of anydesired transverse' configuration.

Other'objects and/or features of the inventio will become self-evident from a further perusal ofthe specification when considered along with the accompanying drawing.

In the drawing:

Fig. 1 is a side elevational View, partly in section, showing one structural embodiment by means of which cane may be produced in accordance with the invention.

Fig. 2 is a sectional View taken on line 2-2 of Fig. 3 is a sectional View taken on line 3--3 of Fig. 1;

Fig. 4 is an enlarged side elevational view of the bait shown in Fig. 1;

Fig. 5 is an end View of Fig. 4;

Fig. 6 is an enlarged view illustrating the manner of construction of the bait support employed.

It has been observed that a freely falling stream of molten glass will fall in a perfectly straight line a limited distance, such distance depending on the working range of the glass, but beyond this distance it will begin taking a wavelike form and finally follow a spiral path. Having these observations in mind the foregoing objects have been successfully accomplished by flowing a freely falling stream of molten glass in small volume on to a movable bait or plug in a laterally confined area of a desired cross-sectional conguration, with the distance between the bait and root of the stream held to a value g acl-aims. (or 49h-3.9i

withinl which, the glass, hows. in a straight line; path,y and' lowering. the bait'. andV its supported" body of glass. caneat'such. a.. rate that the distance between the'top. of the.. formed. pool. andy thel root' of4 the stream. never de viates from a` straight linepath.

Referring tothe drawing in.detail;,molten glass. is, supplied from an suitable supply body,` not showntoa flow spout. I2. Arranged'below spout. I2. is ,aslanting supporti!A pivotally.- moun-tedf at', 9L and provided with an angleadjllstirlg lhk IllI andi a lockingl linl; II. T he. upper. endf oi;support,I 'I carries a die., I Sgwhose bore is., of "a .transverse conf iigurationin accordance with thatofj the glassv shapel desired,v i. e., 4 round oval,' triangulan recgr tangular, square, etc'., andI aV slight, taper whose dimension is largestl at thebottomend; l.to reduce friction b etweenthe' s'et' glass and the die wall; Initially arrangedwithin die; I3 is amovable bait I4 oi a transversecon'guration usually matching that ofI the diebore and having adovetail cavity A18 in its upper. surface. A suitable annealingvlehr I9 alsocnsupportl 'I is arrangedcoextensive with the borer of die4 I3; Baiti I4 isv secured' to one endof'a support comprising a series of rods I-I'I threaded to one another and passing between drive and pressure rollers 20 and 2i arranged beyond the exit end of lehr I9. Roller 20 is adapted to be turned by a belt 22 receiving its drive from a speed reduction unit 23 driven by a motor 24. A suitable motor controller 25 enables close control of the rate of lowering movement of bait I4. The die and bait may be made of a non-wetting alloy comprising approximately 7% to 10% aluminum, less than 7% iron and the balance of copper. Alternatively, the bait and/or die may be made of carbon.

Operation In operation the bait I4 is arranged in the upper end of die I3 a distance from the bottom of spout I2 short enough that any deviation of the stream from a straight line path is avoided, this distance depending on the fluidity and Working range of the particular glass being Worked.

As glass issues from spout I2, the dovetail cavity- I8 in bait I4 first becomes lled, after which a pool is accumulated on the top surface of the bait, and acquires depth after the conning Walls of die'I3 are encountered. As the top level of the accumulated pool begins to rise, motor 24 is started to drive roller 20 at such a rate that the space relationship between the bottom of spout I2 and the top of the accumulated pool of glass is maintained Within the limitations permitted by the character and viscosity of the glass, the space never being allowed to reach that at which spralling is likely to occur. The glass cane thus accumulating within the lateral connes of die I3 is slowly elongated without introducing laps or folds in the accumulated glass. As will be understood, after the operation has continued for some time the bait and set glass cane issue from the die I3. As the operation continues, bait supportingr rods I5 and I6 successively pass between rollers 20 and 2I. Manual lowering of the bait I4 may readily be resorted to after the bait nears the rollers 20 and 2l and until the cane 26 extends therebetween, following Which the rollers 20 and 2| may again be employed to lower the cane at the appropriate rate of speed. As will be observed from an inspection of Fig. 5, the dovetail cavity I8 is of such shape as to enable removal o the bait from the cane simply by moving the bait laterally with respect to the cane.

' As will be appreciated, slight variation in glass viscosity may necessitate changing the rate of lowering of the cane from time to time. This may be accomplished at will by adjustment of the motor controller 25 to suitably readjust the speed of the motor 24. The operation, o course, can be continued indenitely, desired length sections of the work-piece being cracked off and removed frorn the lower end thereof from time to time in any known manner.

It should be understood that the term cane or workpiece, as used herein, is to be interpreted broadly for, as previously brought out, cane of any of various cross-sectional congurations may be produced.

` What is claimed is:

1. The method of forming glass cane which desired outline, progressively lowering the supcomprises flowing molten glass in an unconned y port at the speed necessary to maintain the top surface of the accumulated glass a distance from the root of the stream less than that at which it would spiral, issuing the glass as it becomes set into rigid cane into an unconned area and controlling the downward movement of the accumulated glass and the adjoining rigidly set cane by direct engagement of the latter whereby the formation of cane may be continued indefinitely without interruption.

2. The method of producing glass cane, which includes intercepting near its source a continuous freely falling stream of molten glass of relatively small cross-sectional area to accumulate a pool of molten glass having a cross-sectional area larger than that of said stream, said point of interception being within the distance from the source of the stream beyond which spiraling of the stream would occur, lowering said pool of y molten glass, as it accumulates, at a speed such that the distance between the point of interception of said stream and the source thereof remains less than that at which spiraling of the stream would occur, and maintaining the crosssectional outline of the accumulated molten glass pool constant, as such pool is being lowered, until the molten glass sets to cane.

ROBERT C. CLEVELAND.

WILLIAM HOWARD SAID.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 779,280 Hays Jan. 3, 1905 1,256,980 Chamberlin Feb. 19, 1918 1,673,138 Bicherou June 12, 1928 1,729,147 Blair Sept. 24, 1929 1,805,260 Reece May 12, 1931 2,320,341 Bowes June 1, 1943 

